Axial thrust bearing thickness measuring fixture

ABSTRACT

An axial thrust bearing thickness measuring fixture for accurately comparing the axial thicknesses of two thrust bearing assemblies. The fixture includes a rigid base and a rigid plate. A clamping mechanism releasably interconnects the base and plate. It is operable to clamp the plate and base against opposite radial thrust surfaces of a bearing assembly, which might include one or more shims. Separation between the base and plate then is a function of the effective axial bearing assembly thickness. An indicator may be mounted between the base and plate to record differences in the measured axial bearing thickness.

RELATED APPLICATION

This is a continuation-in-part of pending U.S. application Ser. No.185,127, filed on Sept. 8, 1980 now abandoned.

BACKGROUND OF THE INVENTION

This invention arose from an effort to eliminate the need for specialpurpose tools when reassembling an automobile differential aftersubstituting new axial thrust bearing assemblies within it. This tasktypically requires special factory-supplied tooling, or tedious trialand error methods that require visual matching of gear tooth patterns.As in many other gear applications, it is most important that themeshing gears be reassembled in precisely the positions in which theyhave been previously used, or undesirable wear and noise will resultduring subsequent usage.

The present fixture enables the user to accurately compare the thicknessof any axially shimmed bearing assembly to the thickness of a referencebearing assembly. It is designed specifically for use in conjunctionwith conical axial thrust bearings, which cannot be axially measured byhand, since the bearing elements are not self-aligning and must becompared in thickness under normal axial thrust loading conditions.

The fixture accommodates all the variables that occur in replacingshimmed axial thrust bearings, including minor differences in shimthickness, and mismatches between a bearing and a race. Mismatches arevery frequent, since the bearings and races are typically distributedseparately from one another. In many instances, each might be producedby a different manufacturer.

The present fixture provides a comparison of the axial thicknesses oftwo bearings with or without shims to enable a user to select therequired replacement bearing and shim thickness. It enables the user toaccurately select a new shim combination which will axially locate thebearing to match the previous position of the bearing in the assembledmachinery. It eliminates trial and error and overcomes the usualdifficulties encountered in pressing shims and/or bearings onto and froma mounting shaft. The comparison of the bearing assembly thickness canbe accomplished independently of any shaft assembly, so that the finalshimmed bearing assembly can be utilized with a high degree ofconfidence.

DESCRIPTION OF THE DRAWINGS

A preferred and alternate embodiment of this invention is illustrated inthe accompanying drawings, in which:

FIG. 1 is a side elevation view of the fixture;

FIG. 2 is a top view;

FIG. 3 is a bottom view;

FIG. 4 is a front elevation view;

FIG. 5 is an exploded sectional view taken along line 5--5 in FIG. 2showing loading of the fixture;

FIG. 6 is an enlarged sectional view showing usage of the fixture; and

FIG. 7 is a sectional view similar to FIG. 6, showing usage of thefixture.

PREFERRED EMBODIMENT OF THE INVENTION

In compliance with the constitutional purpose of the Patent Laws "topromote the progress of science and useful arts" (Article 1, Section 8),applicant submits the following disclosure of the invention.

The drawings illustrate one preferred form of the invention. It isdesigned to provide a visual comparison aid for accurately matching thethickness of an axially shimmed thrust bearing assembly, such as oneincluding a conical roller bearing. An exemplary replacement bearingassembly is shown in FIGS. 5 and 7 of the drawings. It includes an innerconical bearing 10, a complementary outer race 11 and an annular shim12. The critical thickness related to repositioning of the bearingassembly is the axial spacing between a first thrust surface on theouter annular shoulder 9 of the race 11, and a second thrust surface onthe opposed shoulder or surface 8 exposed on the shim 12.

A typical original equipment bearing assembly, shown without shims, isillustrated in FIG. 6. It also includes an inner conical bearing 40 anda complementary outer race 41. The critical thickness which must bematched when replacing a worn bearing is the axial spacing between afirst radial thrust surface on the outer annular shoulder 39 of the race41 and a second radial thrust surface on the opposed shoulder 38 ofbearing 40. After continued usage, this spacing will no longer beidentical to original specifications because of wear in the bearingcomponents.

As used herein the term "bearing assembly" shall refer to anycombination of axial thrust bearing components having axially spacedannular thrust surfaces which engage critically spaced working machineelements. The bearing assembly might or might not include axial shims,which are conventionally used to extend the effective axial length ofthe bearing components.

It is understood that this disclosure relates to comparisons between thetotal effective axial thickness of bearing assemblies between opposedradial thrust surfaces which seat a working member. The thrust surfacescan be located either directly on the bearing and/or race, as well as onone or more shims positioned to either or both sides of the bearingcomponents.

The fixture basically comprises a rigid base 13 and an opposed rigidplate 16. Means is provided for clamping the bearing assembly betweenbase 13 and plate 16 so that the axial separation between them isindicative of bearing assembly thickness.

Base 13 is illustrated as being circular in shape and is formed about abase axis X--X (FIG. 5). It includes a first planar inner surfacedesignated generally at 14 and an outer face 15. Similarly, plate 16 isillustrated as being circular in shape and is formed about a plate axisY--Y (FIG. 5). It includes a second planar surface 17 and an outer face18. The planar surface 14 is perpendicular to and centered about thebase axis X--X for engaging one thrust surface of a bearing assembly.Surface 17 is perpendicular to and centered about the plate axis Y--Yfor engaging a second thrust surface of the bearing assembly.

Base 13 includes a rigid post 21 threadably fixed to it. Post 21 iscentered about base axis X--X. Post 21 protrudes outwardly beyond innerface 14 and has a length greater than the anticipated axial separationbetween base 13 and plate 16 when clamped about a bearing asssembly.

Plate 16 has an aperture 19 formed through it and centered along theplate axis Y--Y. Aperture 19 has a cross-sectional configurationcomplementary to that of post 21 and is adapted to freely receive post21. In the case of a cylindrical post 21, as shown, aperture 19 is alsocylindrical and has an inner diameter slightly greater than the outerdiameter of the post 21.

A removable nut 22 threadably engages the outer end of post 21. Itprovides locking means adjustably engageable between the post 21 and theplate 16 when the base 13 and plate 16 are assembled at opposite sidesof a bearing assembly with post 21 extending through both the bearingassembly and aperture 19 (See FIGS. 6, 7). Tightening of nut 22selectively applies a preselected axial clamping force against the twothrust surfaces of a bearing assembly arranged coaxially between base 13and plate 16 with its radial thrust surfaces engaged respectively by thefirst and second planar surfaces 14 and 17 and with post 21 extendingthrough the central bearing aperture. In this completed clampingrelationship, the first and second annular surfaces 14 and 17 of thebase 13 and plate 16 are parallel and abut the opposed radial thrustsurfaces on the working shoulders of the bearing assembly. The axialseparation between the assembled base 13 and plate 16 therefore servesas a physical indicator of the effective bearing assembly thicknessalong the coaxial center axes of base 13 and plate 16.

One of the planar surfaces 14 or 17 is provided with an axially centeredrecess for clearing portions of a bearing assembly protruding axiallyoutward beyond the thrust surface engaged by it. An example is shown byinner bearing 10, which protrudes beyond the thrust surface on shoulder9 of the outer race 11 as illustrated in FIGS. 6 and 7. One or more suchrecesses can be provided.

As shown in the drawings, the recess is formed by a plurality ofcircular surfaces 24 axially centered on surface 17 of plate 16.Surfaces 24 are progressively stepped in depth, or recessed in adirection leading toward the center of plate 16. The stepped annularconfiguration allows the fixture to accommodate protruding bearingconfigurations and to be effectively used for measuring axial thicknessof a wide variety of bearing assemblies having different diameters andaxially protruding cages.

In order to make effective use of the fixture, reference means isprovided on the assembled base 13 and plate 16 for selectivelyindicating their axial positions relative to one another. This is shownas a pedestal 25 that is slidably mounted to base 13 in a directionparallel to the center base axis.

Pedestal 25 includes one or more elongated legs 26 which are receivedthrough complementary apertures formed through base 13 adjacent to post21 and which terminate at one end in inner end flanges 27 adapted toengage the inner face 17 of plate 16. The second ends of the legs 26project beyond base 13 in a direction opposite to their inner ends andare fixed to a rigid transverse bracket 30 which joins them to completean integral rigid pedestal unit. A compression spring 33 encircles post21 and abuts both flanges 27 (FIG. 5). It urges the inner ends of legs26 toward the plate 16 in the assembled fixture.

As one way of providing a visual indication of the relative axialposition between base 13 and plate 16, which is a function of bearingthickness, there is provided an indicator post 31 movably located withinan aperture formed through the bracket 30 across the outer end ofpedestal 25. Post 31 is coaxial with the center base axis and post 21.It can be fixed in place by a manual locking screw 32.

The indicator post 31 serves as an indicating means on the plate 16,while the outer face 15 serves as a second indexing means on the base13. The relative axial positions of these two indexing means can bevisually checked by the relative axial position between the outer face15 on base 13 and the adjustable post 31 on pedestal 25.

In practice, post 31 should initially be free to move axially duringclamping of a worn bearing assembly between base 13 and plate 16 (FIG.6). After nut 22 has been hand tightened, a feeler gauge 20 ofpredetermined thickness can be inserted between post 31 and the adjacentsurface of the outer face 15. Locking screw 32 can then be tightened toaccurately locate post 31 relative to base 13. The user can then recheckthe spatial relationship between base 13 and plate 16 at any subsequenttime by use of the same feeler gauge thickness. Therefore, once the base13 and plate 16 have been axially positioned and the indicator providedon base 25 has been preset, the base 13 and plate 16 can be disassembledand reassembled any number of times with complete confidence that theoriginal setting of the fixture will be properly maintained.

It is the ability to disassemble and reassemble the fixture in thepreset axial separation that permits one to achieve accurate comparisonbetween bearing assemblies prior to fitting a replacement bearingassembly in a machine. As shown in FIG. 7, the replacement componentsand one or more shims can replace the original worn bearing assembly towhich the fixture is preset. By tightening nut 22, one can check theaxial spacing along various combinations of bearing components until theexact spacing of the worn bearing assembly has been matched, as shown inFIG. 7. The use of the same feeler gauge 20 to check the axialpositioning of the fixture components with respect to both bearingassemblies (FIGS. 6 and 7) assures exact duplication of the crucialshoulder separation in a replacement bearing. This in turn will assurethat gears or other worn elements spaced by the replacement bearingassembly will be located in match their wear patterns. Mismatch of wearpatterns in worn elements such as meshing gears would otherwise causevibration, noise and accelerated wear in the reassembled machinery.

It is understood that other alternative indicator devices can beutilized in conjunction with this disclosure. The indication of bearingassembly thickness should be taken coaxially along the center of post21, which will average out variations in bearing assembly thickness fromone side to the other. This can be done with various types ofmicrometers, and with various measuring devices mounted to the base 13,plate 16 and pedestal 25. As an example, a conventional dial indicator(not shown) could be mounted to the pedestal 25 for direct reading ofvariations in axial spacing between base 13 and plate 16.

When using the fixture, one must first preset it to the effective axialthickness of the bearing assembly which is to be replaced. The used orworn bearing assembly, including any bearing shims, is clamped betweenbase 13 and plate 16 as shown in FIG. 6. The nut 22 is hand tightened tosecure the bearing assembly with its opposed annular shoulders parallelto one another. The indicator post 31 can then be accurately set andlocked to the pedestal 25 for future reference.

Once the fixture has been set in this manner, one can verify and matchthe axial thickness of a replacement bearing assembly, including shimthickness as shown in FIGS. 5 and 7. The replacement bearing assemblyand shims can be clamped in the same manner between base 13 and plate16, until it has been verified that the axial thickness of thereplacement is identical to the original. One can then confidently mountthe bearing assembly and shims in place and reassemble the machinerywithin which they are incorporated. The axial positioning of the bearingwill then be identical to the original positioning. This accuraterepositioning can be achieved without the laborious task of pressing theshims or bearing on and off the equipment in which they are to be used.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural features. It is to beunderstood, however, that the invention is not limited to the specificfeatures shown, since the means and construction herein disclosedcomprise a preferred form of putting the invention into effect. Theinvention is, therefore, claimed in any of its forms or modificationswithin the proper scope of the appended claims, appropriatelyinterpreted in accordance with the doctrine of equivalents.

I claim:
 1. An axial thrust bearing thickness measuring fixture forsuccessively engaging individual annular bearing assemblies and forcomparing their effective axial thicknesses to one another while thebearing assemblies are removed from their normal shaft placement, eachbearing assembly having a central aperture formed about a bearing axisand two radial thrust surfaces axially spaced along the bearing axis;said fixture comprising:a rigid base formed about a base axis; a firstplanar surface on said base perpendicular to the base axis for engagingone thrust surface of a bearing assembly; a rigid plate formed about aplate axis;a second planar surface on said plate perpendicular to theplate axis for engaging a second thrust surface of a bearing assembly;one of said planar surfaces being provided with an axially centeredrecess for clearing portions of a bearing assembly protruding axiallyoutward beyond the thrust surface engaged by it; said base furthercomprising a rigid fixed post centered along the base axis andprotruding outwardly beyond said first planar surface; said plate havingan aperture formed therethrough having a cross-sectional configurationcomplementary to that of the post, said aperture being centered alongthe plate axis; locking means engageable between said post and saidplate for selectively applying a preselected axial clamping forceagainst the two thrust surfaces of a bearing assembly arranged coaxiallybetween the base and plate with its thrust surfaces engaged respectivelyby said first and second planar surfaces and with said post extendingthrough its central aperture, the axial spacing between the base andplate then being a function of the bearing assembly thickness; andreference means on said base and said plate, respectively, forindicating their relative axial positions with respect to one anotherwhen assembled with a bearing assembly between them.
 2. An axial thrustbearing thickness measuring fixture for successively engaging individualannular bearing assemblies and for comparing their effective axialthicknesses to one another while the bearing assemblies are removed fromtheir normal shaft placement, each bearing assembly having a centralaperture formed about a bearing axis and two radial thrust surfacesaxially spaced along the bearing axis; said fixture comprising:a rigidbase formed about a base axis; a first planar surface on said baseperpendicular to the base axis for engaging one thrust surface of abearing assembly; a rigid plate formed about a plate axis; a secondplanar surface on said plate perpendicular to the plate axis forengaging a second thrust surface of a bearing assembly; one of saidplanar surfaces being provided with an axially centered recess forclearing portions of a bearing assembly protruding axially outwardbeyond the thrust surface engaged by it; said base further comprising arigid fixed post centered along the base axis and protruding outwardlybeyond said first planar surface; said plate having an aperture formedtherethrough having a cross-sectional configuration complementary tothat of the post, said aperture being centered along the plate axis;locking means engageable between said post and said plate forselectively applying a preselected axial clamping force against the twothrust surfaces of a bearing assembly arranged coaxially between thebase and plate with its thrust surfaces engaged respectively by saidfirst and second planar surfaces and with said post extending throughits central aperture, the axial spacing between the base and plate thenbeing a function of the bearing assembly thickness; and reference meanson said base and said plate, respectively, for indicating their relativeaxial positions with respect to one another when assembled with abearing assembly between them; said reference means comprising apedestal mounted to the base and including a leg freely slidable throughan aperture formed through the base adjacent to said post and parallelto the base axis, said leg having one end abutting said plate.
 3. Anaxial thrust bearing thickness measuring fixture for successivelyengaging individual annular bearing assemblies and for comparing theireffective axial thicknesses to one another while the bearing assembliesare removed from their normal shaft placement, each bearing assemblyhaving a central aperture formed about a bearing axis and two radialthrust surfaces axially spaced along the bearing axis; said fixturecomprising:a rigid base formed about a base axis; a first planar surfaceon said base perpendicular to the base axis for engaging one thrustsurface of a bearing assembly; a rigid plate formed about a plate axis;a second planar surface on said plate perpendicular to the plate axisfor engaging a second thrust surface of a bearing assembly; one of saidplanar surfaces being provided with an axially centered recess forclearing portions of a bearing assembly protruding axially outwardbeyond the thrust surface engaged by it; said base further comprising arigid fixed post centered along the base axis and protruding outwardlybeyond said first planar surface; said plate having an aperture formedtherethrough having a cross-sectional configuration complementary tothat of the post, said aperture being centered along the plate axis; andlocking means engageable between said post and said plate forselectively applying a preselected axial clamping force against the twothrust surfaces of a bearing assembly arranged coaxially between thebase and plate with its thrust surfaces engaged respectively by saidfirst and second planar surfaces and with said post extending throughits central aperture, the axial spacing between the base and plate thenbeing a function of the bearing assembly thickness; said axiallycentered recess comprising a plurality of annular circular surfacesaxially centered on said one planar surface and progressively stepped indepth in a direction leading inward toward its center.
 4. An axialthrust bearing thickness measuring fixture for successively engagingindividual annular bearing assemblies and for comparing their effectiveaxial thicknesses to one another while the bearing assemblies areremoved from their normal shaft placement, each bearing assembly havinga central aperture formed about a bearing axis and two radial thrustsurfaces axially spaced along the bearing axis; said fixturecomprising:a rigid base formed about a base axis; a first planar surfaceon said base perpendicular to the base axis for engaging one thrustsurface of a bearing assembly; a rigid plate formed about a plate axis;a second planar surface on said plate perpendicular to the plate axisfor engaging a second thrust surface of a bearing assembly; said basefurther comprising a rigid fixed post centered along the base axis andprotruding outwardly beyond said first planar surface; said plate havingan aperture formed therethrough having a cross-sectional configurationcomplementary to that of the post, said aperture being centered alongthe plate axis; locking means engageable between said post and saidplate for selectively applying a preselected axial clamping forceagainst the two thrust surfaces of a bearing assembly arranged coaxiallybetween the base and plate with its thrust surfaces engaged respectivelyby said first and second planar surfaces and with said post extendingthrough its central aperture, the axial spacing between the base andplate then being a function of the bearing assembly thickness; andreference means on said base and said plate, respectively, forindicating their relative axial positions with respect to one anotherwhen assembled with a bearing assembly between them, said referencemeans comprising a pedestal mounted to the base and including a legfreely slidable through an aperture formed through the base adjacent tosaid post and parallel to the base axis, said leg having one endabutting said plate.
 5. A fixture as claimed in claim 4 wherein thepedestal leg has a second end projecting beyond said base in a directionopposite to its first end.
 6. A fixture as claimed in claim 4 whereinthe pedestal leg has a second end projecting beyond said base in adirection opposite to its first end; andindicator means mounted to thesecond end of said pedestal leg for indicating relative axial positionsof the base and plate with respect to one another.
 7. A fixture asclaimed in claim 4 further comprising:spring means operably engagedbetween the pedestal and base for urging said one end of the pedestalleg toward said plate.